Xyloglucan endotransglucosylase/hydrolases (XTHs) are a class of cell wall-associated enzymes involved in the construction and remodeling of cellulose/xyloglucan crosslinks. However, knowledge of this gene family in the model monocot Brachypodium distachyon is limited. A total of 29 BdXTH genes were identified from the whole genome, and these were further divided into three subgroups (Group I/II, Group III, and the Ancestral Group) through evolutionary analysis. Gene structure and protein motif analyses indicate that closely clustered BdXTH genes are relatively conserved within each group. A highly conserved amino acid domain (DEIDFEFLG) responsible for catalytic activity was identified in all BdXTH proteins. We detected three pairs of segmentally duplicated BdXTH genes and five groups of tandemly duplicated BdXTH genes, which played vital roles in the expansion of the BdXTH gene family. Cis-elements related to hormones, growth, and abiotic stress responses were identified in the promoters of each BdXTH gene, and when roots were treated with two abiotic stresses (salinity and drought) and four plant hormones (IAA, auxin; GA3, gibberellin; ABA, abscisic acid; and BR, brassinolide), the expression levels of many BdXTH genes changed significantly. Transcriptional analyses of the BdXTH genes in 38 tissue samples from the publicly available RNA-seq data indicated that most BdXTH genes have distinct expression patterns in different tissues and at different growth stages. Overexpressing the BdXTH27 gene in Brachypodium led to reduced root length in transgenic plants, which exhibited higher cellulose levels but lower hemicellulose levels compared to wild-type plants. Our results provide valuable information for further elucidation of the biological functions of BdXTH genes in the model grass B. distachyon.

The formation of adventitious roots plays a key role in plant asexual reproduction, yet research on this process in pepper remains limited. Exogenous auxin treatment substantially promotes adventitious root formation in pepper, and we identified CaLBD16 as a positive regulator acting downstream of auxin signaling. Further analysis revealed that the signal transduction from auxin to CaLBD16 is mediated through the activation of CaARF6 and CaWOX11, both of which also contribute to adventitious root formation. Together, our findings uncover a molecular mechanism underlying auxin-induced adventitious root formation in pepper, offering valuable insights for its practical application in production.

The development of rice flowers and panicles critically affects grain yield and quality. LEAFY HULL STERILE1/OsMADS1, a grass-specific SEPALLATA-like MADS-box transcription factor, is essential for rice floral development and floral meristem activity maintenance. However, the mechanism through which OsMADS1 interacts with other genes to regulate floral organ identity and meristem determinacy remains unclear. In this study, we first generated OsMADS1 knockout mutants using CRISPR/Cas9. The mutant florets exhibited obvious morphological defects, which were categorized into five phenotypic classes. Yeast two-hybrid screening identified two OsMADS1-interacting proteins: OsMADS22, an STMADS11-like protein, and OsYABBY5, a YABBY transcription factor. Their physical interactions were validated both in vitro and in vivo, and were important for floral organ specification and meristem maintenance. Transcriptomic analysis revealed that OsMADS1 regulates numerous genes involved in hormone signaling and panicle/flower development. Furthermore, OsMADS1 acts together with OsMADS22 and OsYABBY5 to modulate the expression of the downstream target OsMADS55, thereby controlling rice spikelet development. Together, our results reveal that OsMADS1 executes diverse regulatory functions in floral organ specification and meristem identity by interacting with multiple developmental regulators, providing new insights into the molecular mechanisms of plant flower development.